A wide pressure range estimate of gas damping in polysilicon inertial MEMS devices

In this paper several 3D numerical approaches are used to provide an estimate of the damping coefficient for complex MEMS starting from atmospheric pressure down to the free-molecule regime. While at standard conditions (p~1 bar), continuum-based methods with slip boundary conditions are adopted, in the free molecule regime two different techniques are compared: a classical Test Particle Monte Carlo method and a Boundary Integral Equation approach. It is shown that, for the class of applications at hand, the results obtained in these two regimes combined with simple bridging formulas can provide a reliable estimate of the damping coefficient in the whole range of possible working pressures.